1. Field of the Invention
The present invention relates to an indirect fired Brayton cycle turbine driven power plant, and more specifically to one that burns a dirty fuel like coal or bio-mass.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
A Brayton cycle turbine engine is a very efficient converter of fuel to energy, and is typically powered by natural gas or a liquid fuel. Coal burning power plants burn coal, the coal being a very cheap source of energy but also contains residue from the combustion process that would damage a turbine if used in the Brayton cycle turbine power plant. Brayton cycle turbine power plants in the past have used heat from burning coal to heat the gas supplied to the turbine, but through a heat exchanger such that the residue from burning coal does not enter the turbine. This heat exchanger is not very efficient in transferring heat, and the maximum operating temperature is limited to what the heat exchanger materials can withstand. The efficiency of a Brayton cycle turbine increases as the temperature of the hot gas stream increases. Coal can burn to produce a very hot gas stream. However, modern day materials used to make heat exchangers cannot withstand this high temperature. Oil based fuels are burned for use in driving Brayton cycle turbines, but the cost of oil based fuels have increased in recent years. Coal is a very abundant and relatively cheap fuel.
U.S. Pat. No. 7,444,818 issued on Nov. 4, 2008 to Brostrneyer and entitled BATCH FIRED HEAT RESERVOIRS discloses a power plant that burns a dirty fuel such as coal to generate heat that is used to drive a turbine and produce electric power, the entire disclosure being incorporated herein by reference. The power plant includes two heat reservoirs that are connected in series so that while the first heat reservoir is being charged with heat, the second heat reservoir is supplying the hot gas flow to the turbine. When the second heat reservoir has been discharged of its stored heat and the first heat reservoir has been recharged with heat, the two are switched so that the newly charged heat reservoir will supply the hot gas flow to the turbine. With this system, the impurities contained in the flue gas (hot gas flow) produced by burning the coal can passed through a turbine to produce electric power. The present invention is an improvement in the heat reservoirs used in this patented invention.
It is therefore an object of the present invention to provide for a power plant that makes use of the very high energy conversion of a Brayton cycle turbine with the relatively cheap and abundant use of coal as the heat producing fuel.
It is another object of the present invention to make use of a dirty fuel like coal or bio-mass that can burn at a very high temperature, and use the heated air in a Brayton cycle turbine for producing power.
It is another object of the present invention to provide for a heat reservoir that will not discharge contaminants in the hot gas flow that will be passed through a turbine.